DESCRIPTION (Taken from the application): The research application aims to study the gene expression pattern of the spirochete Borrelia in the Ixodes tick vector and to comprehend the molecular changes that occur on the spirochetes to facilitate disease transmission. Towards this goal, a novel approach will be utilized to study differential gene expression of tick-adapted spirochetes. Experiments will be carried out to: A) identify genes expressed by the spirochetes at specific feeding time points; B) analyze the temporal and spatial pattern of expression of these genes in an effort to focus on molecules that would be biologically relevant to transmission of disease; and C) to generate mutant Borrelia lacking specific genes of interest identified in this application and test the potential of these mutant Borrelia to transmit disease. The protein products of the genes that are inferred to have a physiological role in disease transmission will ultimately be tested as transmission blocking vaccines. The results of this investigation will enable a better understanding of molecules involved in transmission of Lyme disease and permit novel strategies for the intervention of disease. The investigation will also be conducive to the development of a useful molecular tool/approach to analyze the gene expression patterns of other vector-borne pathogens in their vector environment.